The invention relates to a method for forming at least one suspended nanowire made from germanium-base single-crystal material, a method successively comprising:                providing a substrate comprising a first silicon layer covered by a target layer made from a silicon-germanium alloy-base material,        forming at least one suspended beam in the target layer,        oxidizing thermally the suspended beam so as to form said nanowire, in the place of the suspended beam, by condensation of the germanium atoms.        